Why Polonite filters?

Polonite® phosphorus filter for individual sewage

Phosphorus filters from Polonite Nordic both removes and enables recycling of the essential nutrient phosphorus to productive land. The filters are effective, maintenance-free, and work continuously, as compared to chemical treatment.

How does it work?

Polonite is a reactive calcium silicate with unique features such as the ability to adsorb phosphorus from treated sewage water. When Polonite is used in sewage treatment, the calcium on the filter media adsorbs the phosphorus in the wastewater, and removing the phosphorus.

Phosphorus filter – an ecosystem of nutrients

Polonite phosphorus filter is the only technology known as of today, which both removes and recovers phosphorus, thus creates an ecosystem of nutrients. The saturated filter media can be returned to productive soil with no further pre-treatment. (Certification and regulations may vary between countries.)

Benefits with Polonite phosphorus filter

  • Easy and maintenance-free
  • No chemicals, mechanical parts or electricity is required
  • Compliant with EU requirements on P-removal
  • The treatment is constant and never stops, as compared to chemical precipitation
  • Disinfection integrated

Function and flow

Polonite phosphorus filters are placed at the end of the treatment process, after the septic tank and biological treatment. The filter can be placed in a separate well or as an integrated part of a compact wastewater treatment plant. Treated wastewater is led down to the bottom of the filter where it rises towards the surface with help of hydrostatic pressure. The wastewater flows over the edge of the bag, and out in the well where the filter is placed, before it flows out to recipient.

Installation and maintenance is very simple – the only maintenance required is the change of filter media after approximately 2-5 years of usage.

Polonite® phosphorus filter for larger applications

Unique filter media for large-scale wastewater phosphorus removal and recovery without chemicals

The core in reactive filter beds is so called reactive filter media or reactive sorbent. It is a natural media containing calcium which quickly can react with and uptake a substance that needs to be separated or removed completely. It is usually a mineral based material or residues from the steel and concrete industry. Polonite, xylite, slags or tailings are some examples. Polonite is unbeatable for phosphorus binding and recovery but also for disinfection. The technology is a result of more than 20 years’ research at The Royal Institute of Technology in Stockholm, Sweden.

The high pH-value is a special characteristic of the filter media, which is necessary to bind a several different substances, like phosphorus. The reactive filter media reacts chemically with the unwanted substance in the wastewater and binds it to the media’s grainy surface. The more fine-grained the media is and the bigger surface it has, the more will bind into it.

Large scale phosphorus filter

The requirements on phosphorus removal are increasing and getting stricter. Polonite Nordic’s phosphorus filters, Polonite, binds up to 100% of the phosphorus and is a sustainable alternative as well as a complement to chemical precipitation, primarily in smaller wastewater treatment plants, where chemicals are not an alternative. Levels of phosphorus in incoming water vary between 5 – 20 mg/l. The filter can purify very low levels of phosphorus in the outgoing water, 0,1-0,3 mg/l. The most cost-effective solution are filters for smaller wastewater treatment plants with requirements for 0,5-5 mg/l. The same filter solution can be used for end-polishing as well as phosphorus recovery in reject water.

Installation and management

The solution is to place a phosphorus filter in the end of the treatment process. The installation can be stationary or mobile and where it is possible, the existing basins can be used to lower the investment costs. Polonite Nordic has also developed a container concept with an advanced flow Sequenced Batch Process (SBR) for optimum usage of the filter media. The placement of the containers is adapted to the existing infrastructure and logically optimized. Change and disposal of the used filter media could also be included in the concept, which will be taken care of by a local partner. This means that the saturated filter media with lime, silicon and phosphorus can be recycled on productive soil. (Certification may vary between countries.)

Large scale application at a public WWTP


  • Complete P-removal down to 0.1 mg/l (i.e. reduction rate up to 99,9%)
  • Most effective filter based on research at The Royal Institute of Technology, Stockholm
  • Very effective disinfectant – up to 99.9% of bacterial reduction
  • No need for chemicals
  • Saturated filter makes a great fertilizer and soil conditioner
  • Reduced corrosion of existing infrastructure – low maintenance
  • No additional sludge production

Polishing of reject water

Incoming levels of phosphorus may be as high as 200 – 300 mg/l. The more nutrient the higher the efficiency of the filters. Other technologies used for large scale phosphorus recovery often don’t remove enough of the nutrient. Our filters can easily be combined with these technologies and improve the removal rate.

Suitable for

Polonite is the only solution on the market that provides a sustainable nutrient cycle of phosphorus and is suitable for larger wastewater treatment plants that:

  • lack, or need to improve, existing P-removal
  • want to both remove and recover phosphorus
  • want to replace or complement chemical precipitation and biological P-removal
  • want to reduce total cost for P-removal
  • strive for environmentally sustainable solutions
  • want to implement a process that aligns with future regulations on P-removal and recovery

Application areas for Polonite in a classic flow chart of a WWTW:

For more information, please email info@ecofiltration.se